The manager of a popular Thai news website was detained as she returned from an Internet freedom conference in Europe on charges of insulting the monarchy and violating the Computer Crime Act.

Chiranuch Premchaiporn, webmaster of Prachatai, said she was stopped Friday at an immigration checkpoint at Bangkok’s international airport and shown an arrest warrant issued by police in the northeastern province of Khon Kaen. She had just attended a conference in Hungary dealing with online free expression.

“I’m not sure of what the charges actually are at the moment and I’m afraid I won’t be able to request bail by the end of today,” Chiranuch told The Associated Press.

Thailand’s freedom of speech reputation has taken a battering in recent years, as the government has tried to suppress political opposition that has sometimes turned violent. Its standing in the Press Freedom Index issued by the Paris-based group Reporters Without Borders slipped to 130 last year from 65 in 2002, when the ratings were initiated.

An office worker is seen looking at prachatai.com web site, in Bangkok. Rights groups on Saturday slammed the arrest of the editor of the website as she returned from an Internet freedom conference. AFP

The press freedom group condemned the arrest.

“We call for Chiranuch’s immediate release and the withdrawal of the charges against her so that we do not have to witness another attempt to exploit the Computer Crimes Act to silence the regime’s critics,” it said in an e-mailed statement. “Prachatai is a reliable source of news and information that has managed in recent months to keep the public informed about what is going on in Thailand.”

The arrest was met with scathing comments on Twitter, where Chiranuch _ nicknamed Jiew _ is active.

Chiranuch was sent immediately to formally hear the charges at a police station in Khon Kaen, 275 miles (445 kilometers) from Bangkok.

Police Lt. Col. Thanomsit Wongwijarn said a Khon Kaen man had filed a complaint in early 2009 over some messages posted on Prachatai.

Chiranuch was arrested last year on similar charges, and it was not clear if the new arrest involved the same cases, in which she was blamed for offending messages posted on the site. She has not yet been tried, but faces up to 50 years in prison on the old charges.

Prachatai, which was established by several respected journalists, senators and press freedom activists, describes itself as an independent, nonprofit, daily Web newspaper that provides information “during an era of serious curbs on the freedom and independence of Thai news media.” It was blocked by government censors during anti-government protests earlier this year that demanded Prime Minister Abhisit Vejjajiva call early elections.

Thailand’s lese majeste law mandates a jail term of three to 15 years for “whoever defames, insults or threatens the king, the queen, the heir to the throne or the regent.” The 2007 Computer Crime Act carries a penalty of up to five years’ imprisonment and a fine of 100,000 baht ($3,260).

The act bars the circulation of material deemed detrimental to national security or that causes public panic, and authorities have used it to block thousands of websites deemed insulting to the monarchy.